Langstone Discussion Forum

Forum for discussion about the Langstone Microwave Transceiver that shares some features with the Portsdown. Wiki:
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Joined: Tue Jun 30, 2020 11:59 am

Re: Langstone Discussion Forum

Post by DL5BCA » Sun Aug 02, 2020 11:59 am

Hello Collin,

thank you for the quick implementation. It works fine.

Two things caught my eye:
FM-TX modulation sounds much better. Not so dull anymore .. GREAT.
However, the modulation is relatively quiet. Even if I set the FM Mic Gain to 100%.

I connected Pluto over the network and I often saw dropouts in the waterfall.
Today I then connected the Pluto directly to the Raspi and there are also irregular and lengthy dropouts. I once attached 2 pictures ...

I saw yesterday that Portsdown4 also offers a way to implement the Langstone software.
Unfortunately the Langstone doesn't start with me ... I also had little time to test yesterday ...

Many thanks for the Langstone TRX ... Great, I'm looking forward to becoming a QRV on the higher bands ...
I have a 2m mesh dish for ATV. I want to expand it with a multiband feed and then make it operational ...

73 from northern Germany

Thomas DL5BCA
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73 Thomas

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Re: Langstone Discussion Forum

Post by g4eml » Sun Aug 02, 2020 3:52 pm

Hello Thomas,

I have not changed anything to do with the FM modulation so it should not be any different to before. My system certainly has not changed.
The low modulation level is probably down to your choice of microphone or USB dongle. On my system I can easily get too much deviation!. That is something I need to look at in the future, the GNU Radio NBFM modulator block apparently doesn't have any sort of deviation limiter. Even though there is a setting for 'Maximum deviation' it seems to ignore this.

The internal software gains are already as high as I would like to go, any more and background noise starts to be a problem. You may need to add a microphone pre-amplifier so that the signal starts off at a higher level.

Connecting over a network needs a very good, fast, connection. There are too many variables to be able to comment.

The dropouts on the waterfall are strange, I have never seen that. In fact I do not see how it can happen. The waterfall is only drawn when it receives data from the receive module. With no data it just stops drawing, it does not draw blank lines.

Are you sure you do not have a strong local signal near to the receive frequency? Maybe a 433.9 MHz device? The Pluto has an AGC circuit in the receiver, that will reduce the gain if it sees a very large signal in its passband (which is wider than the Langstone displays). That could cause the Pluto to sometimes send back spectrum data that is below the black level.

If you still have the problem try adjusting the FFT Threshold setting, you may then see that it is due to the gain varying.

As for the Portsdown Integration, I can't really comment on that, I have not tried Dave's latest version. However I don't think I have changed anything that would stop it working.

Colin G4EML

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Joined: Tue Jun 30, 2020 11:59 am

Re: Langstone Discussion Forum

Post by DL5BCA » Mon Aug 03, 2020 6:35 am

Hello Collin

thanks again for your answer.

It is quite possible that I will have to install a microphone preamplifier later.
After I took a larger SD card (4GB not enough), the installation in the Portsdown environment also worked.

Many OMs that work via the QO100, both NB transponders and WB transponders, use a network cable to send the data to Pluto. This is relatively stable and should work well with the Langstone and Portsdown software.

I can't explain this because of the dopsout. I also only tried on 70cm because I have nothing to test on the other frequencies. FFT changes are of no use because nothing is received and therefore nothing is displayed.
I will continue to watch this.

Thank you very much for the effort.

73 Thomas DL5BCA
73 Thomas

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Re: Langstone Discussion Forum

Post by w0iy » Mon Aug 03, 2020 2:55 pm

g0mjw wrote:
Sun Jun 07, 2020 6:50 am
My mouse certainly bounces, sends double steps, but it could be the original encoder and replacement are sufficiently different that it's internal CPU can't cope. Wired mice are less common these days. A solution to this and one without the need for a dismembered mouse in the box might be a microcontroller with a USB interface emulating a mouse. Not sure I know how to make an Arduino do that, but someone else might. I assume it's not possible to do this via GPIO and free up the USB port?

I'm particularly interested in a front panel with real buttons and knobs. Is there a way to get the main code to accept freq and other commands? I can make the panel uC part, but am not familiar with the GNU sw.

Barry w0iy

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Joined: Thu Apr 26, 2018 9:36 am

Re: Langstone Discussion Forum

Post by g4eml » Mon Aug 03, 2020 4:02 pm

The user interface is all controlled by Langstone_GUI.c which is written in conventional C. That is fairly tightly linked to the touch screen control. You would need to modify that quote a bit to work with hardware buttons. The GNU Radio modules would not need changing.

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